The present invention generally relates to methods and apparatus for forming self-repairing interconnections for electrical circuits. More particularly, the present invention relates to an interconnection system using metal-doped chalcogenide material in contact with metal interconnections which heal defects in the metal interconnections.
The performance and cost of electronic systems have improved continuously due in part to advances in manufacturing progressively smaller electronic devices. Advances in semiconductor technology have resulted in a tremendous reduction in the feature sizes of electronic devices, thereby increasing the density of electrical circuits. In fact, over the past two decades, the density of components which can be located on a single microchip has increased by a factor of 100 per decade.
As the density of components has increased, so has the requirement for the density of interconnection pathways formed between these components. In order to increase the density of interconnection pathways the size of interconnections must be reduced. Small geometry interconnections, however, are highly prone to failure by electromigration at points where the lines have a reduced cross-section due to thinning at topographical features (e.g., an underlying step), line narrowing by reflective notching during a photolithography step, and morphological effects such as width variations at grain boundaries after etching. The ultimate quality and reliability of many electronic systems are determined largely by the reliability of the interconnection system.
To mitigate problems associated with high density devices and increase device reliability, metal lines are desirably designed or made wider than the minimum lithographical line width, preferably by a factor of two or more, to reduce current density at the thin regions of the lines and thereby reduce electromigration. Manufacturing devices th wider lines, however, reduces the overall interconnection density for the devices.
Therefore, interconnections capable of healing defects and/or breaks in interconnection pathways are highly desirable to thereby increase overall system reliability.
The present invention relates to methods and apparatus for forming self-healing interconnections for electrical circuits. In accordance with an exemplary embodiment of the present invention, an interconnection metal (e.g., copper, silver, and the like). is deposited on a layer of metal-doped chalcogenide material. When breaks occur in the interconnection metal, the break is healed (i.e., filled in) by the formation of a metal element formed by metal precipitation at the break.